Cardiovascular Disorders



Cardiovascular Disorders





AORTIC ANEURYSM

Athoracic aortic aneurysm is an abnormal widening of the ascending, transverse, or descending part of the aorta. Aneurysm of the ascending aorta is the most common type and has the highest mortality. An abdominal aneurysm generally occurs in the aorta between the renal arteries and the iliac branches.


Causes

Aneurysm commonly results from atherosclerosis, which weakens the aortic wall and gradually distends the lumen. The exact cause is unknown, but there are factors that contribute which are included here:



  • age and family history


  • fungal infection (mycotic aneurysms) of the aortic arch and descending segments


  • bicuspid aortic valve


  • congenital disorders, such as coarctation of the aorta or Marfan syndrome


  • inflammatory disorders


  • trauma


  • syphilis


  • hypertension (in dissecting aneurysm)


  • tobacco use.








CARDIAC ARRHYTHMIAS

Abnormal electrical conduction or automaticity changes heart rate and rhythm. Arrhythmias vary in severity — from mild, producing no symptoms, and requiring no treatment (such as sinus arrhythmia, in which heart rate increases and decreases with respiration), to catastrophic ventricular fibrillation, which mandates immediate resuscitation. Arrhythmias are generally classified according to their origin (ventricular or supraventricular). Their effect on cardiac output and blood pressure, partially influenced by the site of origin, determines their clinical significance. (See the appendix “Types of cardiac arrhythmias.”)


Causes

Each arrhythmia may have its own specific cause. Common causes include:



  • congenital defects


  • myocardial ischemia or infarction


  • organic heart disease


  • drug toxicity


  • degeneration or obstruction of conductive tissue


  • connective tissue disorders


  • electrolyte imbalances


  • hypertrophy of heart muscle


  • acid-base imbalances


  • emotional stress.








CARDIAC TAMPONADE

Cardiac tamponade is a rapid, unchecked rise in pressure in the pericardial sac that compresses the heart, impairs diastolic filling, and limits cardiac output. The rise in pressure usually results from blood or fluid accumulation in the pericardial sac (pericardial effusion). Even a small amount of fluid (50 to 100 mL) can cause a serious tamponade if it accumulates rapidly.


Causes



  • Idiopathic


  • Effusion (due to cancer, bacterial infections, tuberculosis, or, rarely, acute rheumatic fever)


  • Traumatic or nontraumatic hemorrhage


  • Viral or postirradiation pericarditis


  • Chronic renal failure requiring dialysis


  • Drug reaction (procainamide, hydralazine, minoxidil, isoniazid, penicillin, or daunorubicin)


  • Heparin- or warfarin-induced tamponade


  • Connective tissue disorders


  • Postcardiac surgery


  • Acute myocardial infarction (MI)


  • Pericarditis







CARDIOMYOPATHY

Cardiomyopathy is classified as dilated, hypertrophic, or restrictive.

Dilated cardiomyopathy (DCM) results from damage to cardiac muscle fibers; loss of muscle tone grossly dilates all four chambers of the heart, giving the heart a globular shape.

Hypertrophic cardiomyopathy (HCM) is characterized by disproportionate, asymmetrical thickening of the interventricular septum and left ventricular hypertrophy.

Restrictive cardiomyopathy (RCM) is characterized by restricted ventricular filling due to decreased ventricular compliance and endocardial fibrosis and thickening. If severe, it’s irreversible.


Causes

Most patients with cardiomyopathy have idiopathic disease, but some are secondary to these possible causes:



  • viral infection


  • long-standing hypertension


  • ischemic heart disease or valvular disease


  • chemotherapy


  • cardiotoxic effects of drugs or alcohol


  • metabolic disease, such as diabetes or thyroid disease.







CONGENITAL DEFECTS

The most common congenital defects of the heart are atrial septal defect (ASD), coarctation of the aorta, patent ductus arteriosus (PDA), tetralogy of Fallot, transposition of the great arteries, and ventricular septal defect (VSD). Causes of all six defects remain unknown, although some have specific clinical associations.


ATRIAL SEPTAL DEFECT

An opening between the left and right atria permits blood flow from the left atrium to the right atrium rather than from the left atrium to the left ventricle. ASD is associated with Down syndrome.




COARCTATION OF THE AORTA

Coarctation is a narrowing of the aorta, usually just below the left subclavian artery, near the site where the ligamentum arteriosum joins the pulmonary artery to the aorta. Coarctation of the aorta is associated with Turner’s syndrome and congenital abnormalities of the aortic valve.




PATENT DUCTUS ARTERIOSUS

The ductus arteriosus is a fetal blood vessel that connects the pulmonary artery to the descending aorta, just distal to the left subclavian artery. Normally, the ductus closes within days to weeks after birth. In PDA, the lumen of the ductus remains open after birth. This creates a left-to-right shunt of blood from the aorta to the pulmonary artery and results in recirculation of arterial blood through the lungs. PDA is associated with premature birth, rubella syndrome, coarctation of the aorta, VSD, and pulmonic and aortic stenosis.





TETRALOGY OF FALLOT

Tetralogy of Fallot is a combination of four cardiac defects: VSD, right ventricular outflow tract obstruction, right ventricular hypertrophy, and an aorta positioned above the VSD (overriding aorta). This defect is associated with fetal alcohol syndrome and Down syndrome.




TRANSPOSITION OF GREAT ARTERIES

The aorta rises from the right ventricle and the pulmonary artery from the left ventricle, producing two noncommunicating circulatory systems. This defect is associated with VSD, VSD with pulmonic stenosis, ASD, and PDA.




VENTRICULAR SEPTAL DEFECT

VSD is an opening in the septum between the ventricles that allows blood to shunt between the left and right ventricles. However, the defect is usually small and will close spontaneously. VSD is associated with Down syndrome and other autosomal trisomies, renal anomalies, prematurity, fetal alcohol syndrome, PDA, and coarctation of the aorta.







CORONARY ARTERY DISEASE

Coronary artery disease (CAD) results from the narrowing of the coronary arteries over time because of atherosclerosis. The primary effect of CAD is a diminished supply of oxygen and nutrients to myocardial tissue because of decreased blood flow.



Causes



  • Atherosclerosis (most common)


  • Dissecting aneurysm


  • Infectious vasculitis


  • Syphilis


  • Congenital abnormalities


  • Radiation to the chest



Sep 22, 2018 | Posted by in ANATOMY | Comments Off on Cardiovascular Disorders
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